Fine Mapping Of Extreme Resistance Gene Rychc To Potato Virus Y

Research Background Previous studies exhibited that Rychc is a single dominant gene,resistance to PVY.Resistance to PVY population?F1?was obtained by the interspecific cross between S.chacoense acc.40-3?Resistance to PVY?and S.berthaultii acc.143-6?Susceptible to PVY?and the offspring separation ratio was 1:1.This study early we have screened 8 closely linked SNP makers and locked this gene at about 2 Mb segment at the end of potato chromosome 9.Afterwards,she screened 3 genetic markers which were closely linked to Rychc,that were M32,M152 and M236.This project was designed on the basis of this research,and the main research results were as follows:Primary mapping for Rychc Based on the phenotype and genotype of the recombinants which were selected by M32,M152 and M236 to screened 142 offspring of primary mapping group.We mapped Rychc between SNP maker solcap_snp_c2₄8042 and genetic maker M32.There were about 834 kb in this segment based on V4.03 DM1-3 database of reference genome of potato.By using bioinformatics prediction,there were about 110 genes in this segment.There are only one recombinant?A128?between the left maker SNP S48042 and Rychc,and three recombinants between the right maker M32 and Rychc.Development of new makers on the left of Rychc In order to verify the reliability of left maker S48042 of primary mapping and screened more recombinants,we developed new maker based on PCR amplification on the left of Rychc.We designed 17 genetic makers on the left of the target gene,found only one specific genetic maker M4 based on PCR amplification,which was closely linked to Rychc.We found only one recombinant?A128?among 142 offspring of primary mapping group.Finally,we verified the reliability of left maker S48042 of primary mapping.Screened more recombinants and identified their phenotype We used left maker M4 and right one M32 to screened 1078 descendants of fine mapping group.Finally,we screened 12 recombinants and the recombinating rate is only about 1.38%.After that,we used the method of virus vaccination to test their phenotype.The results of ELISA test showed that there were ten recessive plants and two resistance plants.Fine mapping for Rychc Firstly,we continued to develop specific makers in the section of primary mapping.We designed 110 genetic makers between M4 and M32 and screened 8 tightly linked makers to Rychc.Then,we used these makers to screen 142 descendants of primary mapping group and 12 recombinants,combined with the phenotype of recombinants and their combinated positions in chromosome,we mapped Rychc between genetic maker M2526-2 and M48-6.Finally,we narrowed down the mapping section from 834 kb to 120 kb.Bioinformatic prediction of the sequences of fine mapping section On the basis of bioinformatics it is predicted that there were about 22 genes in 120 kb segment of fine mapping section according to DM 1-3 sequences,including 6 genes with typical structure domain of R gene,and they were distributed in clusters.